Luminescence of Er3+-doped nanostructured SiO2–LaF3 glass-ceramics prepared by the sol–gel method

Transparent glass ceramics with composition of 95SiO2–5LaF3 doped with 0.1 mol% of Er3+ were synthesized by thermal treatment of precursor sol–gel glasses. Segregated LaF3 nanocrystals in the glass were confirmed from a structural analysis performed by X-ray diffraction. Blue, green and red efficient up-conversion emissions were observed under 980 nm excitation at room temperature. Under this excitation near infrared down-conversion at 1.55 μm is also observed. These results could be attributed to the precipitation of LaF3 nanocrystals and the incorporation of most Er3+ ions in these nanocrystals. The mechanisms involved in the up-conversion emissions could be ascribed to two and three photon processes.